It helps a LOT to be really clinically strong and up-to-date; that gains you the respect of the students and of the staff at clinical agencies. But, it may not be enough, especially if you want to be a truly excellent educator. Education is a different area, and deserves lots of respect too. Some of us who do not have training in nursing education do catch on, or learn as we go form peers, mentors, by attending conferences, or from just reflecting on our own past experiences as learners. You may also have been a preceptor to nurses in the past, which gives you the perspective that different people learn in different ways.
If you have a chance, take a course or two on active learning strategies, on test development and analysis, etc. Learning how to write good, accurate exams is a real challenge--it is NOT something you can pick up on the job easily, and it is not fair or your students to practice on them as you get the hang of it. Attend QSEN, so you will be up-to-date, and realize that what we teaches nurses needs to shift so that they can become key members of a HC system that focuses on high quality, safe, effective, culturally sensitive, patient-centered care. Read the report on The Future of Nursing, and Benner's book, Educating Nurses. Nurisng education is going through some major changes right now, so prepare yourself to teach nursing in different ways and with a different focus than in the past.